Effect of Dose-Dependent Application of Fungicides Propineb and Mancozeb on H2O2, Lipid Peroxidation, and Photosynthetic Pigment in Tomato Leaves

Objective: The study investigated the growth, photosynthetic pigment, hydrogen peroxide (H2O2), and malondialdehyde (MDA) contents of tomato leaves under different concentrations of two modern fungicides, mancozeb and propineb. Materials and Methods: Tomato plants were cultivated for 45 days and irrigated with ¼ Hoagland solution. Three different concentrations of propineb and mancozeb; half of the recommended dose (1.5 g/L and 1 g/L), recommended dose (3 g/L and 2 g/L), and two times higher (6 g/L and 4 g/L) sprayed on tomato leaves, respectively. After the fungicide treatment, tomato leaves were harvested at 1, 3, and 7 days after the treatment (DAT). Results: The highest doses of propineb and mancozeb inhibited shoot growth compared with the control at 7 DAT. The chlorophyll a, b and carotenoid contents were significantly reduced with all mancozeb and propineb treatment doses at 3 and 7 DAT. The phytotoxic effects of fungicides were determined by H2O2 and MDA content 1, 3, and 7 days after treatment in leaves. The foliar application of propineb and mancozeb altered the production of H2O2 and MDA, depending on the time and concentration. The analysis of the data revealed that the application of propineb and mancozeb at higher concentrations significantly increased H2O2 and MDAlevels, which caused toxicity in tomato leaves.Conclusion: The findings revealed that higher doses of mancozeb and propineb fungicides exert phytotoxic effects by inhibiting growth and photosynthetic pigment production and increasing oxidative stress in tomato leaves.